1. Field of the Invention
This invention relates to novel platinum complexes which have high potencies for use as an antitumor agent.
2. Statement of the Prior Art
It is already known that certain platinum complexes have an antitumor effect. For instance, cis-dichlorodiammine platinum (II) (general name: cis-Platin) has a very excellent antitumor effect and is widely used clinically at present (see, for instance, Journal of Phamaceutical Science, Vol. 65, No. 3, pp. 315-328, 1976, and Inorganic Biochemistry, Vol. 11, pp. 139-149, 1979). However, cis-Platin has strong side effects such as renal toxicity and vomitting toxicity and has also low solubility in water, which merely allows supply of liquid preparations of a low concentration. These problems have been the obstacles to the wider application of this compound in clinical therapeutics.
Recently, some new platinum complexes such as cis-1,1-cyclobutane dicarboxylato-diammine platinum [Japanese Patent Application Kokai (Laid-Open) No. 49-48621] and cis-O,O'-glycolato-diammine platinum [Japanese Patent Application Kokai(Laid-Open) No. 59-222497] have been developed.
These newly developed compounds, however, are disappointedly low in antitumor activity in comparison with cis-Platin. Therefore, a request has been voiced in the art for the obtainment of a platinum complex which has a strong antitumor activity, few side effects and high solubility in water.